The molecular weight of a gas that has a density of 5.75 g/L at STP is g/mol.

Question

Quizplus · Accepted Answer

The density of a gas at STP (standard temperature and pressure: 0°C and 1 atm) is 1.27 g/L. Thus, a gas with a density of 5.75 g/L at STP has a molecular weight that is about 4.5 times greater than that of air, which has a molecular weight of 28.97 g/mol. Therefore, we can estimate that the molecular weight of the gas is around 130 g/mol. The only choice close to this value is B (129), which is the correct answer.

The Molecular Weight of a Gas That Has a Density